EXENT® GAM Assay
Overview
What is the EXENT GAM Assay?
The EXENT GAM Assay is a sensitive and specific immunoassay that identifies and quantifies M-proteins based on their unique molecular mass. Sample preparation uses paramagnetic beads specific to human IgG, IgA, IgM, total Kappa and total Lambda to isolate immunoglobulins from patient serum. The isolated immunoglobulins are analyzed by MALDI-ToF mass spectrometry to specifically measure the monoclonal protein component. The assay is used in conjunction with the Binding Site Optilite® IgG, IgA and IgM assays to provide semi quantification / reporting in g/L of identified monoclonal proteins.
A new paradigm for the detection & isotyping of M-proteins
Monoclonal protein detection using mass spectrometry
Each plasma cell produces a unique immunoglobulin
Immunoglobulin molecules consist of two identical heavy chains and two identical light chains (Kappa or Lambda)
When immunoglobulins have their inter-chain disulphide bonds reduced, they are dissociated into their constituent heavy and light chains. The reduced light chains from the intact immunoglobulins are ideally suited to analysis by MALDI-ToF mass spectrometry due to their low molecular weight
The resulting mass spectra reflects the plot of mass vs intensity of the isolated and reduced immunoglobulins
| (A) When immunoglobulins are isolated from the serum of a healthy individual, by specific immunopurification, the resulting MALDI-ToF mass spectrometry resolves three normally distributed peaks that are representative of the polyclonal Lambda, Kappa and heavy Kappa free light chains derived from the intact immunoglobulins.1 |
| (B) In a patient with a monoclonal gammopathy, the presence of a sharp peak within the polyclonal background is indicative of the presence of a monoclonal immunoglobulin. The molecular weight of the identified peak can be used to specifically track the monoclonal protein and the peak area ratio of the monoclonal to polyclonal can be combined with the Optilite IgG, IgA or IgM assay to report a result in g/L. |
When a monoclonal protein is identified, a simple calculation is applied to provide a test result in g/L based on the total immunoglobulin value derived from the Optilite IgG, IgA or IgM assay.
The EXENT GAM Assay can be used to:
- Aid in evaluation of monoclonal gammopathy of undetermined significance (MGUS)
- Aid in the diagnosis of smoldering multiple myeloma (SMM), multiple myeloma (MM), waldenström's macroglobulinemia (WM) and AL amyloidosis
The assay empowers clinicians to effectively diagnose patients with monoclonal gammopathies with a simple serum test. This offers the opportunity to:
- Confirm M-protein and M-protein isotype at diagnosis with enhanced sensitivity when serum protein electrophoresis suggests an M‑protein or when serum free light chains are abnormal2
- Identify monoclonal proteins based on their unique molecular mass, providing reduced ambiguity in result interpretation
- Have diagnostic confidence and disease clarity through clear and objective results, with automated peak picking
- Identify clinically relevant information such as post translational modifications and secondary clones
Request with baseline serum sample
EXENT GAM Assay
The baseline serum sample is critical to identify a patient’s M-protein along with its unique molecular mass. This can be used to accurately monitor the specific M-protein at subsequent timepoints during treatment.
Measure with baseline serum sample
Measure follow-up samples using the EXENT GAM Assay
Once the patient's M-protein has been identified, it can be reported. Report this clone but do not report other oligoclonal (transient) peaks as the clinical significance of peaks <0.2 g/L in a diagnostic setting is not well understood. Record the M-protein for future analysis and tracking.
Review Results
Report relevant/persistent clones(s) with EXENT GAM Assay
Review and record the patient's M-protein for future analysis and tracking. Other oligoclonal (transient) peaks may be included as a comment as the clinical significant of oligoclonal peaks is not well understood.
Release
- Report final results to the request clinician or laboratory
- Save patient results in database for future analysis
Related content
This product is not commercially available in China. Future commercial availability cannot be guaranteed.
EXENT and Optilite are registered trademarks of The Binding Site Group Limited (Birmingham, UK) in certain countries.
The EXENT® System combines EXENT® Analyser with Immunoglobulin Isotypes (GAM) for the EXENT® Analyser.
EXENT GAM Assay refers to Immunoglobulin Isotypes (GAM) for the EXENT® Analyser.
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References
- Barnidge DR, et al. Subset of kappa and lambda germline sequences result in light chains with a higher molecular mass phenotype. J Proteome Res 2015; 14:5283-90
- Immunoglobulin Isotypes (GAM) for the EXENT Analyser Instructions for Use